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UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  NO.  156 

I 


INSECTS  INJURIOUS  TO  STORED  GRAINS 
AND  THEIR  GROUND  PRODUCTS 


BY  A.  A.  GIRAUL,T 
ASSISTANT  TO  STATE  ENTOMOLOGIST 


URBANA,  ILLINOIS,  JULY,  1912 


CONTENTS  OF  BULLETIN  No.  1 56 

PAGE 

Granary  Moths 69 

The  Angoumois  Grain  Moth  (Sitotroga  cerealella  Ol.) 69 

The  Mediterranean  Flour-moth  (Ephestia  kuehniella  Zell.) 72 

The  Indian  Meal  Moth  (Plodia  interpunctella  Hiibn.) 75 

The  Meal  Snout-moth  (Pyralis  farinalis  Linn.) 76  a 

Granary  Beetles  and  Weevils 77 

The  Confused  Flour-beetle  ( Tribolium  confusum  Duv.) 77 

The  Saw-toothed  Grain-beetle  (Silvanus  surinamensis  Linn.) 79 

The  Granary  Weevil  (Calandra  granaria  Linn.) 80 

The  Rice-weevil  (Calandra  oryza  Linn.) 81 

The  Yellow  Meal-worm  (Tenebrio  molitor  Linn.) 82 

Measures  of  Prevention  and  Remedy 83 

Treatment  of  Infested  Grain 84 

Fumigation  with  Hydrocyanic  Acid  Gas 85 

Fumigation  with  Carbon  Bisulfid 87 

The  Use  of  Cold  and  Heat 89 

Contact  Insecticides  89 

A  Key  for  the  Identification  of-  Granary  Insects. 90 


INSECTS  INJURIOUS  TO  STORED  GRAINS  AND 
THEIR  GROUND  PRODUCTS 

BY  A.  A.  GIRAUL/T,  ASSISTANT  TO  STATE  ENTOMOLOGIST 

It  is  well  known  that  many  kinds  of  insects  live  in  wheat  and 
other  grains  and  in  meal  and  flour,  either  accompanying  the  grain 
to  the  granary  from  the  field,  or  going  to  it  after  it  is  stored. 
Many,  indeed,  go  with  it  from  the  producer  to  the  customer — 
thru  cribs,  elevators,  mills,  and  warehouses,  to  the  retail  store,  and 
thence  to  our  homes.  Insects  of  these  habits  are  particularly  hardy, 
and  many  are  so  far  omnivorous  that  they  may  live  and  multiply  on 
food  which  seems  to  us  to  contain  no  nourishment.  All  are  either 
beetles  or  their  larvae,  or  the  larvae  of  moths.  The  latter  are  of 
fewer  kinds  but  of  greater  capacity  for  mischief  than  the  former. 
At  any  particular  time  and  place,  half  a  doz.en  to  a  dozen  of  these 
insects  may  be  present,  working  in  various  ways,  some  of  them, 
indeed,  not  directly  injurious  but  feeding  on  chaff  or  other  granary 
debris,  and  obnoxious  merely  by  their  presence.  Of  the  others, 
one  or  more  may  be  injuring  individual  kernels  of  grain  in  a  way 
to  make  them  unfit  for  food  and  to  prevent  their  growing  if  sown ; 
or  one  may  be  webbing  together  flour  and  meal  in  mills,  making 
them  useless  for  food,  and  also  clogging  some  parts  of  the  machinery 
by  webbing  together  masses  of  flour.  Further  harm  may  be  done 
by  causing  fermentation  in  the  stored  grain.  The  percentage  of 
actual  injury  may  not  be  large  for  the  whole  mass  infested,  but 
the  mere  presence  of  considerable  numbers  of  these  insects  reduces 
the  value  of  the  grain  or  flour,  and  may  interfere  seriously  with 
its  sale. 

Over  fifty  species  live  habitually  or  occasionally  in  stored  cereals 
and  cereal  products  in  the  United  States,  but  only  about  ten  of 
these  are  of  the  first  importance.  Seventeen  are  habitual  grain 
eaters,  but  the  food  of  the  others  is  comparatively  miscellaneous, 
including  granary  rubbish,  decomposing  substances,  cloth  materials, 
and  dried  animal  matter.  Those  which  are  regarded  as  of  prime 
importance  are  the  Angoumois  grain  moth,  the  Mediterranean  flour- 
rhoth,  the  Indian  meal  moth,  the  meal  snout-moth,  the  confused 
flour-beetle,  the  granary  weevil,  the  rice-weevil,  the  saw-toothed 

67 


68 


BULLETIN   No.   156 


[July, 


grain-weevil,  and  the  yellow  meal-worm.  Of  the  eight  remaining 
habitual  grain  eaters,  about  two  thirds  are  closely  related  to  one 
or  more  of  the  preceding,  but  specifically  distinct  and  less  numerous. 


Fig.  i. 


Ear  of  corn  injured  by  Angoumois  Grain  Moth,  Sitotroga 
cerealella. 


Among  the  forty  species  which  are  classed  as  miscellaneous  in  their 
food  habits,  some,  such  as  the  carpet-beetles,  are  usually  house- 
hold insects,  and  others  infest  museums,  while  a  large  number 
simply  enter  the  granary,  not  merely  because  it  contains  grain,  but 


INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS 


69 


for  shelter  and  for  other  food,  including  such  substances  as  the 
dirt  in  the  cracks  of  the  floors,  bits  of  broken  grain,  dead  insects, 
insect  castings,  molds,  cobwebs,  and  cloth;  or  they  may  feed  occa- 
sionally on  grain  alone.  Many  of  these  insects  are  introduced 
species,  of  cosmopolitan  range,  and  are  scattered  abroad  in  ship- 
ments of  stored  grain  and  other  products. 


GRANARY  MOTHS 

THE  ANGOUMOIS  GRAIN  MOTH 
(Sitotroga  cerealella  Ol.) 

A  characteristic  example  of  the  work  of  this  insect  is  an  ear  of 
corn  peppered  with  small  round  holes,  often  two  or  three  to  a  single 
kernel  (Fig.  i).  These  are  produced  by  a  caterpillar  which  has 
eaten  out  the  embryo  and  the  other  soft  parts  of  the  seed  and  has 
then  cut  through  the  top  of  the  grain  a  small  round  hole  which  it 
has  covered  with  a  web.  In  the  cavity  within  the  kernel  it  changes 
to  the  moth,  and  then,  breaking  thru  the  delicate  silk  cover  closing 
its  burrow,  it  makes  its  way  to  freedom  and  takes  flight. 


Fig.  2. 


Angoumois  Grain  Moth,  Sitotroga  cerealella:  a,  imago   (X5)  ',   b,  pupa 
(X  13)  ;  c,  grain  of  corn  with  a  portion  of  surface  removed  to 
show   injury    ( 


70  BULLETIN    No.    156  [July, 

DESCRIPTION 

This  insect  belongs  to  the  Lepidoptera,  or  family  of  moths,  the 
young  of  which  are  called  caterpillars.  This  species  is  commonly 
known  to  grain  men  as  the  fly-weevil — a  very  inappropriate  name 
because  it  is  not  in  any  sense  a  fly. 

The  eggs  laid  by  the  female  on  the  kernel  are  at  first  milky 
white,  but  soon  turn  to  a  pale  reddish.  They  are  elongate,  slightly 
bottle-shaped,  about  a  fortieth  of  an  inch  long,  with  a  roughened 
surface  which,  when  magnified,  is  seen  to  be  marked  with  minute 
rectangles  in  regular  rows,  giving  them  a  resemblance  to  ears  of 
corn. 

The  recently  hatched  caterpillar  eats  its  way  into  the  lower  end 
of  the  grain,  making  a  barely  visible  round  hole,  which  is  the  less 
noticeable  because  it  is  covered  over  with  silk.  The  caterpillar 
begins  to  feed  at  once  on  the  starchy  material  surrounding  the 
embryo,  and  destroys  the  latter  by  the  time  it  has  itself  become 
full-grown.  (Fig.  2,  c.)  It  is  then  about  a  fifth  of  an  inch  long, 
whitish,  with  a  brownish  head.  A  more  complete  description  fol- 
lows. 

When  first  hatched  the  larva  is  no  thicker  than  a  hair,  but  when 
full-grown  it  is  rather  robust  and  gradually  tapers  backwards  from 
the  second  segment.  The  head  is  brown,  its  lateral  margins  and 
the  ocellar  region  are  light,  and  the  anterior  margin  is  a  little 
darker.  The  mandibles  are  strong,  brown,  bisetose,  quadridentate, 
the  lower  tooth  the  larger  and  the  size  of  the  others  gradually 
diminishing  upward.  The  other  mouth-parts  and  the  antennae  are 
brown,  the  latter  short,  three-jointed,  and  ending  in  a  bristle.  The 
six  ocelli  are  white,  and  arranged  in  the  form  of  an  elongate  letter 
C,  with  the  inclosed  space  varying  from  very  dark  brown  to  nearly 
black.  On  the  head,  body,  and  legs  are  sparsely-placed  white, 
setaceous  hairs,  those  on  the  head,  the  first  and  last  segments,  and 
the  legs,  rather  long.  On  segments  two  to  twelve  inclusive  these 
hairs  are  less  prominent,  and  are  arranged  in  two  transverse  rows, 
those  of  the  anterior  row  much  the  shorter.  On  the  first  and 
thirteenth  segments  the  hairs  of  the  two  rows  are  of  equal  length. 
The  body  is  white,  smooth,  and  densely  covered  with  minute,  erect 
spinules.  In  some  examples  traces  of  brown  patches  appear  on  the 
back  of  the  first  segment.  The  spiracles,  dorsal  hooks,  and  minute 
terminal  hooks  on  the  prolegs  are  brown.  The  legs  are  large  at 
the  base,  but  taper  rapidly,  each  ending  in  a  small  hook.  The  ten 
prolegs  are  small  and  wartlike,  and  each  end  in  two  or  three  minute, 
robust  hooks. 

The  pupa  (Fig.  2,  &)  is  about  a  fifth  of  an  inch  long,  brown- 
ish, pointed  ovate,  with  the  adult  appendages  outlined  thru  the 
crust  along  its  under  surface.  The  wing-pads  nearly  reach  the 
tip  of  the  abdomen.  The  head  end  is  obtuse;  the  posterior  end 


1912}          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  71 

more  acute,  and  surrounded  by  a  ring  of  sparse  setse.  The  head, 
thorax,  and  wing-pads  are  dark,  the  abdomen  lighter  brown.  Eyes 
in  mature  pupae  black,  and  distinctly  visible.  On  the  abdomen  are . 
several  rows  of  setae,  as  follows:  a  double  row  on  the  side,  above 
the  spiracles,  placed  in  pairs;  a  single  row  just  below  the  spiracles 
and  close  to  them ;  another  double  row  on  each  side  of  the  middle 
line  of  the  body,  the  outer  hair  of  each  pair  being  on  the  posterior 
part,  and  the  inner  one  on  the  anterior  part  of  the  segment.  There 
are  two  long,  slender,  conspicuous  bristles  on  the  segment  im- 
mediately behind  the  head. 

The  adult  (Fig.  2,  a),  familiar  to  most  elevator  men,  is  a 
delicately  built,  small  moth,  with  a  quick  wavering  flight,  which 
may  be  seen  in  infested  rooms  resting  on  bags  of  grain,  walls, 
windows,  or  the  like.  It  is  about  three  eighths  of  an  inch  long,  and 
grayish  clay-yellow  when  at  rest,  but  with  hind  wings  dark  grayish 
or  neutral  gray,  and  bordered  with  close,  exceedingly  delicate, 
silvery  fringes.  Each  fore  wing  bears  a  black  dot  between  its  base 
and  its  middle. 

LIFE    HISTORY 

When  bred  indoors  the  generations  of  this  insect  become  con- 
fused, all  stages  being  represented  at  once;  but  in  the  field  there 
are  two  generations,  which  become  adult  in  May  or  June  and  in 
August  respectively.  Where  ear  corn  is  infested  in  the  crib  the  eggs 
are  placed  in  the  groove  of  the  kernel  on  the  ear,  usually  beneath 
the  membrane  which  ensheathes  the  tip  of  each  kernel.  Wheat 
may  become  infested  by  the  second  brood  of  moths  either  thru  eggs 
laid  in  the  field  on  the  grain  in  the  head  or  else  after  storage  in  the 
granary,  and  a  generation  may  develop  from  these  eggs  within 
five  or  six  weeks.  If  an  infestation  begins  in  the  field  and  the 
infested  grain  is  carried  to  the  granary,  the  moths  come  to  maturity 
and.  continue  to  breed  in  the  stored  grain  as  long  as  the  weather 
will  permit;  and  the  same  is  true,  of  course,  if  the  grain  is  first 
infested  after  it  has  been  stored.  If  the  temperature  of  the  store- 
house is  kept  up  by  artificial  heat,  as  in  some  warehouses,  develop- 
ment may  be  continued  thruout  the  winter;  otherwise  the  female 
may  deposit  from  sixty  to  ninety  eggs,  which  hatch,  as  a  rule,  in 
I'rom  four  to  ten  days,  according  to  temperature. 

DISTRIBUTION,   INJURIES,   AND   ENEMIES 

This  moth,  first  noticed  in  France,  is  widely  distributed  in  the 
United  States  and  Europe.  In  this  country  it  is  most  abundant  in 
the  southern  states  and  where  artificial  heat  promotes  its  multiplica- 
tion in  the  northern  granary. 

Wheat  may  be  as  badly  infested  by  this  moth  as  corn,  the  heart 
of  each  grain  being  eaten  out.  Other  cereals  are  injured  less  com- 


72  BULLETIN    No.    156  .         [July, 

monly,  and  cow-peas  are  sometimes  infested  by  it.  While  the 
caterpillar  is  still  young,  infested  kernels  can  not  be  distinguished 
except,  perhaps,  by  their  light  weight.  Later,  however,  a  visible 
hole  is  made  in  the  grain  after  the  caterpillar  is  full-grown. 

The  larvae  of  this  species  are  infested  by  at  least  one  parasite, 
and  also  by  a  minute,  predaceous  mite  (Pediculoides  ventricosus 
Newp.).  This  latter  sometimes  breeds  in  infested  grain  to  an 
extent  to  become  enormously  abundant.  By  its  infinitesimal  bites 
it  irritates  the  human  skin,  causing  a  rashlike  and  sometimes  rather 
severe  eruption,  very  annoying  to  harvest  hands,  grain-house  em- 
ployees, and  others  having  to  do  with  the  handling  of  grain. 

This  grain  moth  may  be  most  readily  destroyed  by  fumigation 
with  carbon  bisulfid  as  described  on  another  page. 

THE  MEDITERRANEAN  FLOUR-MOTH 
(Ephestia  kuehniella  ZellJ 

When  wheat  flour  in  mills  is  webbed  together  in  more  or  less 
irregular,  matted  masses  (Fig.  3),  very  likely  to  cause  trouble  by 
clogging  the  mill  machinery,  the  presence  of  the  Mediterranean 
flour-moth  is  to  be  inferred.  The  adult  of  this  insect  is  a  small 
moth  or  miller,  harmless  in  that  stage,  however,  and  injurious  only 
as  a  larva.  Its  caterpillars  make  tubes  of  silk  in  which  they  live, 
covering  them  with  flour  upon  which  they  feed.  When  full-grown 
they  discard  this  tube  and  wander  about  in  search  of  suitable  places 
in  which  to  pupate,  spinning  silk  as  they  crawl,  thus  webbing  the 
flour  together.  Preparatory  to  pupation  a  cocoon  is  also  spun  of 
silk  matted  with  flour,  which  adds  to  the  nuisance  created  by  their 
presence. 

DESCRIPTION 

The  egg  of  this  insect  is  a  little  more  than  a  sixtieth  of  an  inch 
in  length,  elongate-oval,  white  and  almost  smooth  when  freshly 
deposited,  but  later  becoming  roughened  and  darker. 

The  caterpillar  (Fig.  4,  a,  d,  e)  is  about  a  half  to  three  fifths 
of  an  inch  long,  when  full-grown,  and  varies  from  whitish  to  pink- 
ish in  general  color.  The  surface  is  sprinkled  with  short  whitish 
hairs  rising  from  minute  but  prominent  tubercles. 

The  pupa  (Fig.  4,  b}  is  cylindrical,  tapering  posteriorly,  with 
a  cluster  of  small  hooklets  at  the  tip  of  the  abdomen.  It  is  reddish 
brown  above,  the  head  and  thorax  the  darkest,  and  much  lighter 
below,  approaching  a  yellowish  tint  on  the  wing-pads  and  abdomen. 
The  tip  of  the  last  segment  is  considerably  darker  than  the  rest 
of  the  body.  The  cocoon  (Fig.  5)  varies  in  length  from  two  fifths 
of  an  inch  to  half  an  inch,  and  is  about  a  fourth  of  an  inch  in 
width.  It  is  composed  of  delicate  silk,  often  intermingled  with 


1912]          TNSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS 


73 


Fig.  3.     Mass  of  flour  held  together  by  larval  webbing  of 
Mediterranean   Flour-moth,  Ephestia  kuehniella. 


Fig.  4.     Mediterranean  Flour-moth,  Ephestia  kuehniella:  a,  larva 
b,  pupa;    c,  adult;    d,   fore   part   of   larva;    e,  middle   seg- 
ments  of   larva;    f,    adult    in    resting   position. 
Enlarged  as  indicated.     (U.   S.  Dept. 
of  Agriculture.) 


74  BULLETIN    No.    156  [July, 

particles  of  meal,  flour,  dirt,  or  other  material.     The  pupa  yields 
the  adult  in  about  two  weeks. 


Fig.  5.     Mediterranean  Flour-moth,  Ephestia  kuehniella:  a,    cocoon 

from  attached  side,  showing  pupa  thru  thin  silk 

wall;  b,  outer  side  of  same. 

The  adult  moth  (Fig.  4,  c,  /)  is  about  half  an  inch  in  length, 
and  about  seven  eighths  of  an  inch  from  tip  to  tip  across  the  ex- 
panded wings.  The  front  wings  are  medium  gray,  sprinkled  with 
blackish  scales  and  specks,  and  with  a  V-  or  W-shaped  black  line 
crossing  about  a  third  of  the  distance  from  the  base.  The  hind 
wings  are  silvery  whitish,  with  a  darker  border.  Both  pairs  of 
wings  are  heavily  fringed. 

LIFE    HISTORY,    HABITS,    AND    INJURIES 

This  insect  breeds  thruout  the  year  when  the  temperature  per- 
mits. The  female  may  deposit  as  many  as  two  hundred  eggs, 
which  are  placed  singly  in  flour,  in  cracks  of  the  floor,  and  in  various 
places  about  the  machinery  of  the  mill.  These  eggs  hatch  in  a  little 
more  than  a  week,  on  an  average,  the  period  being  of  course  length- 
ened if  the  weather  is  cool.  The  caterpillars  may  get  their  growth 
in  about  forty  days,  and  the  pupa  yields  the  adult  in  about  eleven 
days.  Approximately  eight  weeks  are  thus  necessary  to  the  devel-^ 
opment  of  a  generation,  with  a  variation  of  a  week  or  more  in 
one  direction  or  the  other  according  to  the  temperature.  The  adults 
live  a  little  over  a  week.  They  have  been  known  to  fly  at  least  six 
or  seven  rods  from  the  place  of  emergence.  They  are  active  at 
night,  but  are  not  attracted  to  lights. 

Altho  wheat  flour  is  most  commonly  infested,  the  larvse  of 
this  moth  are  found  also  in  rice  flour,  buckwheat  flour,  crackers, 


1912}          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  75 

cotton-seed,  corn-meal,  oatmeal,  rolled  wheat,  and  other  prepared 
cereals.  They  sometimes  live,  it  is  said,  in  the  nests  of  bumble- 
bees, and  in  the  hives  of  the  honey-bee. 

The  Mediterranean  flour-moth  is  common  and  widely  distributed 
on  both  sides  of  the  world.  It  was  first  detected  in  Illinois  in  1894. 

The  economic  importance  of  this  insect  is  shown  by  a  state- 
ment made  by  Dr.  F.  H.  Chittenden,  of  the  United  States  Depart- 
ment of  Agriculture,  in  a  recent  circular  of  the  Bureau  of  En- 
tomology on  this  pest  (No.  112,  issued  March  7, 1910),  in  which  he 
says  that  'this  flour  moth  is  attracting  more  attention  than  any 
insect  that  ever  infested  mills  or  other  buildings  where  cereals  are 
stored;  indeed,  it  is  almost  the  sole  topic  of  complaint  of  millers 
at  the  present  writing,  correspondence  in  regard  to  weevils  and 
flour  beetles,  which  was  at  one  time  heavy,  having  fallen  off  very 
noticeably.  *  *  * 

"As  to  the  losses  caused  directly  and  indirectly  by  this  insect, 
it  has  been  difficult,"  he  adds,  "to  obtain  estimates,  the  lowest 
being  between  $100  and  $200  to  a  mill  of  1,000  barrels  capacity. 
The  average  loss  due  to  closing  down  the  mill  and  cost  of  treat- 
ment seems  to  be  not  far  from  $500  for  each  fumigation,  'to  say 
nothing  of  the  loss  to  business,'  according  to  one  Kansas  milling 
firm.  An  estimate  of  $1,000  for  two  fumigations  can  not  be  far 
from  right."  *  *  *  Thus,  cleanliness  in  and  about  the  mill, 
and  care  in  examining  returned  bags  and  other  materials  entering 
it,  will  go  far  towards  preventing  or  diminishing  trouble  from  this 
moth. 

TREATMENT 

Where  a  mill  is  already  infested,  all  flour  or  other  mill  products 
containing  the  insect  should  be  promptly  burned,  and  all  spouts, 
elevator  legs,  other  parts  of  machinery  and  other  equipment,  as 
also  the  walls,  ceiling,  and  especially  the  corners  in  every  part  of 
the  building,  should  be  thoroly  cleaned.  Such  thoro  cleaning  must 
be  followed  by  fumigation  with  hydrocyanic  acid  gas,  or  by  the 
use  of  artificial  heat,  both  of  which  operations  are  described  farther 
on  in  this  paper  under  the  head  of  Measures  of  Prevention  and 
Remedy. 

THE  INDIAN  MEAL  MOTH 

(Plodia  inter punctella  HiibnJ 

With  habits  somewhat  like  those  of  the  Mediterranean  flour- 
moth,  but  occurring  usually  on  the  grain  itself  or  else  in  meal,  the 
caterpillar  of  this  insect  does  most  of  its  injury  by  spinning  silk 
over  whatever  food  it  chances  to  be  feeding  on.  It  may  construct 
a  silken  tube  to  live  in,  or  simply  spin  its  web  in  every  direction. 
Bags  of  grain  may  thus  become  completely  covered  with  closely 
matted  silk,  which  it  is  practically  impossible  to  remove,  so  that 


76 


BULLETIN   No.   156 


[July, 


the  grain  must  be  rebagged  before  shipment.    The  caterpillar  also 
spins  a  cocoon  in  the  midst  of  its  food  materials. 


Fig.  6.     Indian  Meal   Moth,  Plodia  interpunctella :    a,   adult  moth ; 

b,  dorsal  view  of  larva;  c,  side  view  of  larva;  d,  pupa, 

ventral   view.     Enlarged   as   indicated. 

The  egg  of  the  moth  is  whitish,  and  very  small.  The  cater- 
pillar (Fig.  6,  b,  c}  is  dull  olive-greenish,  varying  to  pinkish  or 
whitish,  and  its  elliptical,  cylindrical  cocoon  is  olive-green  varying 
to  light  brown.  The  moths  (Fig.  6,  a)  are  active  creatures,  the 
outer  two  thirds  of  their  fore  wings  reddish  brown  and  the  center 
copper,  while  the  inner  or  basal  third  is  dirty  grayish.  They 
measure  about  five  eighths  of  an  inch  across  the  expanded  wings. 

The  generations  of  this  insect  are  irregular,  and  vary  in  number 
according  to  the  temperature.  The  female  may  lay  as  many  as 


i<)i2\          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS          76 a 

(The  text  of  this  intercalated  page  should  immediately  precede  the  heading 
Granary  Beetles  and  Weevils,  on  page  77.) 

THE  MEAL  SNOUT-MOTH 
(Pyralis  farinalis  Linn.) 

Hidden  away  in  whatever  substance  is  infested  by  it,  the  cater- 
pillar of  this  beautiful  moth  is  seldom  seen.  Its  habits  are  some- 
what similar  to  those  of  the  Mediterranean  flour-moth  in  that  it 
lives  within  a  silken  tube,  but  it  is  more  indiscriminate  in  its  food. 
Thus  it  may  feed  upon  the  chaff  from  shelled  corn  in  preference  to 
the  corn  itself.  Its  silken  tube  is  finely  made,  and  completely  cov- 
ered by  attached  particles  of  the  food. 

The  adult,  or  moth,  of  this  species  is  really  a  very  beautiful 
insect.  Its  wings  are  delicately  colored,  the  base  and  outer  por- 
tions of  the  front  wings  are  brownish,  and  the  whole  of  the  middle 
portion  is  dusky  whitish.  Two  wavy  whitish  lines  cross  these 
wings  separating  the  light  middle  section  from  the  brownish  basal 
and  apical  parts.  The  hind  wings  are  dusky  whitish,  with  two 
wavy  whitish  lines  running  thru  them  and  with  a  few  brownish 
spots  of  varying  size  near  the  hind  margin.  The  eggs  are  laid  in 
masses  and  are  irregular  in  shape.  The  caterpillar  is  dirty  grayish 
in  appearance,  darker  at  both  ends,  the  head  brownish  red.  The 
pupa  is  brownish  red  and  is  enveloped  by  a  cocoon. 

The  life  history  of  this  insect  is  not  well  known,  but  there  are 
probably  at  least  four  or  five  generations  in  a  season.  Under  ordi- 
nary conditions  a  generation  has  been  known  to  develop  in  eight 
weeks  in  spring,  and  a  shorter  period  may  be  expected  at  higher 
temperatures. 

Altho  a  general  feeder,  this  insect  seems  nevertheless  to  prefer 
waste  matter,  in  damp  places — accumulations  of  straw,  chaff,  meal, 
or  other  waste  products  from  the  granary  or  mill,  occurring  in 
corners,  outhouses,  and  the  like.  It  has  also  been  reported  to  feed 
on  hay,  straw,  corn,  clover,  seeds,  dried  plants,  the  grains  and  their 
products,  and  vegetable  garbage. 

Again,  thoro  cleanliness  in  regard  to  accumulations  of  rubbish 
in  corners  and  so  on,  is  prophylactic  against  this  insect,  and  usually 
all  that  is  required  when  the  premises  become  infested  is  cleaning 
up  and  burning  the  infested  material.  If  this  is  not  possible,  one 
should  fumigate  with  carbon  bisulfid,  or  use  artificial  heat. 


1912}          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  77 

three  hundred  and  fifty  eggs,  either  one  by  one  or  in  clusters  of  a 
dozen  or  more.  These  eggs  may  hatch  in  four  days,  under  favor- 
able temperature  conditions,  and  a  generation  may  mature  in  about 
five  weeks. 

The  food  of  this  species  is  not  limited  to  grain,  flour,  or  meal, 
but  includes  such  materials  as  preserved  and  dried  fruits,  peas, 
beans,  edible  nut-meats,  chocolate  beans,  spices,  sugars,  yeast  cakes, 
and  some  kinds  of  dried  roots  and  barks.  When  infesting  grains, 
this  caterpillar  eats  out  the  embryo,  leaving  the  rest -of  the  kernel. 
A  single  larva  will  destroy  a  dozen  or  more  grains,  according  to 
its  size,  and  when  thus  engaged  it  spins  its  silk  over  everything  in 
its  immediate  vicinity. 

The  species  is  found  everywhere  in  the  United  States. 

Fumigation  with  carbon  bisulfid  or  with  hydrocyanic  acid  gas, 
or  the  use  of  artificial  heat,  are  the  standard  measures  for  the 
destruction  of  this  as  of  most  other  insect  pests  of  the  granary 
and  the  mill. 

GRANARY  BEETLES  AND  WEEVILS 

The  hard-bodied  insects  known  as  beetles  and  weevils  differ 
from  granary  moths  in  having  biting  jaws  and  horny  wing-covers 
inclosing  the  membranous  lower  wings.  They  pass  thru  the  same 
stages  of  development  as  the  moths,  but  in  the  young,  active  stage, 
tho  similar  to  caterpillars,  they  may  be  commonly  distinguished 
by  the  absence  of  abdominal  legs.  In  the  third,  or  pupal,  stage, 
they  are  not  protected  by  a  cocoon,  and  are  usually  white,  with  the 
appendages  free.  Unlike  the  moths,  the  adult  beetles  and  their 
larvae  usually  occur  together,  feeding  on  the  same  substances. 

THE  CONFUSED  FLOUR-BEETLE 
(Tribolium  confusum  DuvJ 

Any  small,  shining,  reddish  brown  beetle,  about  an  eighth  of 
an  inch  long,  crawling  about  in  large  numbers  in  flour,  meal,  or 
prepared  cereals,  is  almost  certainly  this  insect.  It  is  a  flattened, 
oval  beetle  with  the  head  and  upper  parts  of  the  thorax  densely 
covered  with  minute  punctures,  and  with  the  wing-covers  ridged 
lengthwise  and  sparsely  punctured  between  the  ridges.  Its  very 
minute  eggs  are  white.  The  wormlike  larvae  are  cylindrical,  wiry, 
white  tinged  with  yellowish,  and  about  three  sixteenths  of  an  inch 
long.  The  pupa  is  white. 

Altho  this  insect  is  extremely  common,  living  on  almost  any 
kind  of  vegetable  debris,  its  life  history  is  imperfectly  known.  Its 
eggs  are  said  to  hatch  within  six  days  at  most  favorable  temper- 
atures, and  the  larvae  to  reach  their  growth  in  twenty- four  days 


78 


BULLETIN    No.    156 


Vuly, 


and  the  pupa  in  six — making  a  period  of  about  five  weeks  for  ithe 
development  of  a  generation  from  the  egg.  Four  or  five  genera- 
tions may  occur  in  a  year,  on  an  average,  the  number  being  de- 


Fig.   7.     Confused   Flour-beetle,    Tribolium   confusum,   adult.     X  24. 


Fig.   8.     Confused  Flour-beetle,   Tribolium  confusum:   a,  larva    (X  24)  ; 

b,  head  of  larva,  greatly  enlarged   (dorsal  view)  ;  c,  anal  end 

of    larva,    greatly   enlarged    (dorsal   view) ;    d,   pupa 

(X  24)  ;  e,  lateral  appendage,  greatly  enlarged. 

pendent,  however,  upon  the  temperature,  since  development  con- 
tinues as  long  as  this  is  favorable.  This  beetle  is  commonly  found 
in  oatmeal,  corn-meal,  prepared  wheat  and  flour,  seeming  to  have 
a  preference  for  these  breakfast  foods.  It  is  by  no  means  limited 
to  such  materials,  however,  but  has  been  reported  from  such  sub- 
stances as  ginger,  peanuts,  beans,  peas,  orris  roots,  cayenne  pepper, 


INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS 


79 


baking-powder,  and  snuff.  Corn  and  wheat  are  also  often  infested 
by  it,  beetles  and  larvae  feeding  upon  the  grains  together,  the 
former,  in  fact,  being  perhaps  more  destructive,  and  certainly  more 
active,  than  the  larvae. 

This  species  occurs  all  over  the  United  States,  and  is  cosmo- 
politan in  its  range. 

Another  beetle,  called  the  rust-red  flour-beetle  (Tribolium  fer- 
rugineum  Fabr.),  less  common  than  the  preceding,  is  often  found 
with  it,  being  similar  to  it  both  in  habits  and  in  appearance.  It 
is  specifically  different  in  the  shape  of  the  head  and  the  terminal 
joints  of  the  antennae.  It  is  also  more  southern  in  its  distribution. 

These  insects  may  be  killed  in  the  grain  by  the  use  of  heat,  or 
by  fumigation  with  insecticide  vapors,  as  is  elsewhere  described; 
and  all  valueless,  infested  material  should  be  gathered  up  and 
burned. 

THE  SAW-TOOTHED  GRAIN-BEETLE 
(Silvanus  surinamensis  LinnJ 

A  minute,  flattened,  chocolate-brown  beetle,  with  the  margins 
of  its  thorax  roughened  with  toothlike  projections,  if  found 
abundant  in  groceries  or  other  edible  substances,  may  be  assumed 
to  be  this  grain-beetle.  The  slender  adult  is  not  more  than  a  tenth 
of  an  inch  long.  The  thorax  is  marked  with  two  longitudinal 


Fig.  9.     Saw-toothed  Grain-beetle,  Silvanus  surinamensis:  a,  adult: 

b,  pupa,  under -side;  c,  larva.     Enlarged  as  indicated. 

(U.  S.  Dept.  of  Agriculture.) 

grooves,  one  on  each  side,  and  with  six  minute  teeth,  like  those 
of  a  saw,  on  each  lateral  edge.  The  head  and  thorax  are  densely 
covered  with  fine  punctures,  and  the  wing-covers  are  finely  punc- 
tured and  lined.  The  larva  is  somewhat  flattened,  with  transverse, 
rectangular,  yellowish  spots  above,  margined  with  the  white  of  the 


80  BULLETIN    No.    156  [July, 

general  body-color.  On  the  thorax  and  anterior  abdominal  seg- 
ments, a  white  line  divides  the  rectangles  into  squares.  The  pupa 
is  white,  and  is  occasionally  inclosed  within  a  delicate  cocoon  com- 
posed largely  of  particles  of  the  food  substance.  From  five  to  seven 
generations  of  this  species  may  be  developed  within  a  single  year, 
the  number  depending,  as  usual,  upon  the  temperature  and  upon 
the  supply  of  food.  The  beetles  infest  almost  anything  of  a  veg- 
etable nature  used  as  human  food,  including  preserved  fruits  and 
various  cereals,  bread,  nuts,  seeds,  red  pepper,  yeast,  spices,  sugar, 
flour,  and  also  tobacco  and  snuff. 

This  beetle  is  widely  distributed,  and  virtually  cosmopolitan  in 
its  range.  At  the  Columbian  Exposition  in  1893  it  was  found  in 
exhibits  of  food  products  from  Brazil,  Argentina,  Paraguay, 
Trinidad,  Mexico,  Greece,  Italy,  Tunis,  Liberia,  and  Java.  It  is 
generally  distributed  in  North  America. 

THE  GRANARY  WEEVIL 
(Calandra  granaria  LinnJ 

Corn  or  wheat,  the  kernels  of  which  contain  a  small,  fat,  leg- 
less, whitish  grub,  somewhat  like  those  commonly  found  in  nuts, 
but  of  much  smaller  size,  is  infested  either  with  this  insect  or  the 
closely  related  rice-weevil,  next  discussed.  The  beetle  (Fig.  10) 
is  about  an  eighth  of  an  inch  long,  ovate,  convex,  and  uniformly 
chestnut-brown,  the  thorax  with  elongate  punctures  in  more  or 
less  definite  lengthwise  rows,  and  the  wing-covers  finely  grooved 
and  ridged  lengthwise.  The  head  is  prolonged  into  a  stout  probos- 


Fig.    10.     Granary  Weevil,   Calandra  granaria,   adult.     X  25. 

cis-like  snout  bearing  the  elbowed  antennae  attached  to  its  sides. 
The  minute  white  egg  is  placed  in  a  cavity  made  in  a  kernel  of 
wheat  or  corn  for  the  purpose.  There  is  usually  but  a  single  grub 
to  a  grain  of  wheat,  but  there  may  be  as  many  as  two  or 
three  in  a  kernel  of  corn.  As  the  beetles  are  unable  to  fly, 
they  do  not  infest  the  ripened  grain  in  the  field.  There  may  be 
four  or  five,  or  even  more,  successive  generations  in  a  year,  each 
requiring  about  forty  days  for  its  development.  As  the  adults 


INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  81 

may  live  six  months  or  more  if  abundantly  supplied  with  food, 
several  generations  commonly  coexist  in  badly  infested  grain. 
Such  grain  is  unfit  for  human  consumption,  and  as  it  can  not  be 
separated  from  that  which  is  uninjured,  it  is  often  a  total  loss. 

Treatment  by  heat,  and  fumigation  with  carbon  bisulfid,  are 
the  standard  methods  of  destruction. 

The  species  is  widely  distributed  in  the  United  States,  but  is 
more  common  southward. 

THE  RICE-WEEVIL 
(Calandra  oryza  LinnJ 

The  beetle  of  this  species  (Fig.  n)  differs  from  the  granary 
weevil  in  being  slightly  smaller  and  of  a  duller  brown,  and  by 
having  on  .the  wing-covers  four  more  or  less  distinct  reddish  spots, 
two  at  the  front  angles  and  two  near  the  tips.  It  is,  moreover,  able 
to  fly.  It  varies  in  color,  from  light  brown  to  black,  and  its  thorax 


Fig.  ii.    The  Rice-weevil,  Calandra  oryza,  adult.     X  25. 

is  densely  covered  with  minute  circular  punctures  not  arranged  in 
longitudinal  lines.  In  its  early  stages  it  is  so  similar  to  the  preceding 
species  that  a  careful  technical  description  is  necessary  to  separate 
them. 

This  beetle,  having  the  power  of  flight,  may  infest  the  grain 
in  the  field  even  before  this  is  fully  ripe.  A  single  female  may 
produce  as  many  as  four  hundred  eggs,  and  altho  the  sexes  fre- 
quently pair,  reproduction  sometimes  occurs  without  this  prelim- 
inary. The  grub  hatching  from  the  egg  is  creamy  white  with  a 
brownish  head.  The  pupa  is  at  first  white,  but  turns  to  brown- 
ish as  the  beetle  develops  within.  It  is  formed  in  a  definite 
cavity  or  cell  within  an  infested  grain.  Development  may 
be  greatly  retarded,  or  even  arrested,  by  cold  weather,  the 
insect  living  on  in  whatever  stage  it  may  have  reached.  A  genera- 
lion  may  develop  in  three  to  six  weeks,  according  to  temperature. 
The  larvae  may  reach  full  size  in  about  sixteen  days. 

This  weevil  is  especially  troublesome  southward,  where  it  in- 
fests corn  in  the  field  and  afterwards  in  the  crib.  The  beetles  begin 


82  BULLETIN    No.    156  [July, 

to  deposit  their  eggs  in  the  South,  early  in  June,  and  continue  until 
the  corn  is  ripe,  adults  emerging  in  about  a  month  after  the  eggs 
are  placed.  This  weevil  may  infest  most  of  the  cereals,  and  is 
especially  common  in  rice.  It  has  also  been  found  in  tobacco,  in 
boxes  of  crackers  and  cakes,  in  macaroni,  and  other  bread  stuffs, 
and  in  barrels  of  flour  and  bags  of  meal.  Its  effect  on  ears  of 
corn  infested  by  it  resembles  closely  that  of  the  Angoumois  grain 
moth,  and  as  many  as  three  or  four  may  live  and  mature  in  a  single 
kernel  of  that  plant. 

THE  YELLOW  MEAL-WORM 
(Tenebrio  molitor  LinnJ 

This  is  a  cylindrical,  yellowish,  shining  grub  (Fig.  10,  u) 
about  an  inch  long  when  full-grown,  with  the  general  appearance 
of  a  thick  wireworm,  often  found  in  stored  flour,  meal,  bran,  and 
other  similar  material.  The  adult  belongs  to  the  family  known  as 


Fig.    10.     Yellow   Meal-worm,    Tenebrio   molitor,   larva,   seen    from 

above. 

darkling  beetles  (Tenebrionidce'),  because  they  avoid  the  light. 
They  do  not  infest  crops,  and  are  economically  important  only  as 
they  occur  in  stored  products  intended  for  consumption  by  man  or 
beast.  The  beetle  of  this  species  (Fig.  12)  is  about  five  eighths 
of  an  inch  long,  somewhat  flattened,  with  head  and  thorax  minutely 
punctured,  .and  with  longitudinal  raised  lines  on  the1  wing-covers. 
The  eggs  are  deposited  singly  or  in  small  clusters  in  the  food  sub- 


Fig,    n.     Yellow   Meal-worm,    Tenebrio   molitor,   larva,    side   view. 

stance  of  the  grubs.  They  may  hatch  in  about  two  weeks.  The 
young  grub  is  white  at  first,  but  gradually  turns  to  yellowish,  darker 
at  each  end  and  also  at  the  end  of  each  segment.  It  may  complete 
its  growth  in  about  three  months.  There  is  but  a  single  generation 
in  a  year,  the  beetles  emerging  in  April,  May,  and  June.  They  are 
nocturnal  in  habit,  flying  about  at  night.  The  grubs  commonly 
get  their  growth  by  fall  or  early  winter,  remain  more  or  less  active 


1912} 


INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS 


83 


during  the  winter  season,  and  pupate  in  early  spring,  to  emerge 
several  weeks  later  in  the  beetle  stage.     The  meal-worm  feeds  on 


Fig.  12.     Yellow  Meal-worm,  Tenebrio  molitor,  adult. 

flour,  meal,  and  even  the  dust  and  refuse  of  mills  and  granaries. 
It  has  sometimes  been  found  in  ship's  biscuit,  and  will  doubtless 
infest  similar  cooked  foods  exposed  to  its  invasion. 

A  closely  related  species  known  as  the  dark  meal-worm  (Tene- 
brio obscurus  Linn.J  is  extremely  similar  to  the  foregoing,  but  dull 
pitchy  black.  In  habits  and  economic  relations  this  is  a  close  parallel 
to  the  preceding,  altho  the  larva  has  been  taken  in  more  unusual 
substances,  such  as  cotton-seed,  commercial  soda,  cotton-seed  meal, 
black  pepper,  and  commercial  fertilizer.  Both  these  species  avoid 
the  light,  and  are  most  likely  to  breed  in  dark  unclean  corners  of 
mills  and  elevators.  Thoro  cleanliness  is,  consequently,  an  im- 
portant preventive. 

MEASURES  OF  PREVENTION  AND  REMEDY 

Insects  of  the  granary  are  much  more  easily  kept  out  than  put 
out.  All  places  where  grain  or  any  of  its  products  are  stored 
should  above  all  things  be  kept  clean — not  merely  apparently  clean, 
but  actually  so.  Cracks  in  the  walls  and  floor,  for  example,  may 
seem  to  be  clean  \vhen  swept  over,  but  may  really  be  filled  with  the 
dust  of  grain  and  similar  debris  and  thus  become  a  breeding  place 
for  a  number  of  granary  insects.  Storage  rooms  and  bins  should, 
in  fact,  be  so  constructed  as  to  be  free  from  cracks,  the  walls,  floor, 
and  ceiling  smooth,  and  everything  solid  and  snug.  No  rubbish 
of  any  kind  should  be  allowed  to  accumulate,  either  in  the  building 
or  on  adjacent  premises.  Everything  should  also  be  done  to  keep 
insects  out  of  the  storehouse.  Grain  should  be  brought  in  from 
the  field  as  soon  as  possible,  since  the  longer  it  is  exposed  after 
ripening  the  more  likely  is  to  become  infested  by  the  Angoumois 
grain  moth,  the  rice-weevil,  and  some  other  species.  If  found  in- 


84  BULLETIN    No.    156  [July, 

fested  when  brought  in  from  the  field,  it  should  at  once  be  fumi- 
gated with  carbon  bisulfid  in  a  room  especially  constructed  for  the 
purpose  in  a  manner  to  be  described  later.  In  the  management  of 
mills,  returned  bagging,  second-hand  machinery,  and  the  like, 
should  be  carefully  inspected  or,  better,  regularly  fumigated. 

The  more  important  special  measures  which,  used  alone  or  in 
combination,  may  prevent  infestation  by  granary  pests,  may  be 
described  as  follows. 

1.  Small  grain  should  be  threshed  and  stored  as  soon  after 
ripening  as   possible.      Wheat   should  be   harvested   and  threshed 
directly  from  the  shock  if  practicable,  but  if  stacked,  should  not 
stand  in  the  field  longer  than  is  absolutely  necessary. 

2.  The  place  intended  for  the  reception  of  a  crop  should  be 
thoroly  cleaned  out  some  time  in  advance,  and  if  there  is  reason  to 
suppose  that  it  has  contained  granary  pests,  it  should  be  fumigated 
with  sulphur.     Complete  protection  against  weevils  requires  that 
rooms  for  grain  should  be  made  tight,  with  windows  screened  and 
doors  close-fitting,  and  also  that  they  should  be  cool  and  dry.    With 
proper  care  and  some  additional  expense,  any  such  structure  can 
be  made  gas-tight  and  suitable  for  the  fumigation  of  its  contents 
with  carbon  bisulfid,  but  the  need  of  thoro  ventilation  should  not 
be  left  out  of  account. 

3.  If  it  were  possible  to  dry  grain  from  the  field  artificially  at 
a  temperature  of  125°  F.  for  four  or  five  hours,  all  insects  would 
be  killed  and  the  grain  could  then  be  stored  in  a  thoroly  clean  and 
tight  place,  and  safely  left  until  needed  for  shipment  or  use.     Corn 
which  has  been  shelled  dry  and  sacked  is  much  safer  than  that  left 
on  the  ear,  whether  with  or  without  the  husks.     Grain  stored  for 
seed  should  be  dried  artificially,  since  it  not  only  keeps  better  and 
germinates  more  generally,  but  it  is  also  less  liable  to  be  eaten  by  such 
insects  as  devour  the  kernel. 

4.  Farmers,   seedsmen,   and  millers  should,   in  buying  grain, 
make  sure  that  it  is  free  from  insects. 

TREATMENT  OF  INFESTED  GRAIN 

When  a  mill  or  storeroom  full  of  grain  has  become  infested 
with  granary  insects,  an  inspection  should  first  be  made  as  to  the 
nature  and  extent  of  the  infestation.  Much  time  and  money  may 
often  be  saved  in  this  way,  for  the  trouble  may  prove  to  be  of 
slight  practical  importance,  and  capable  of  being  remedied  by  some 
simple  and  inexpensive  operation.  A  seed-corn  warehouse,  for  ex- 
ample, may  be  so  generally  infested  by  several  insects  that  it  would 
seem  that  serious  damage  must  have  been  done,  but  it  may  be  found 
that  the  more  abundant  of  these  insects  are  feeding  on  dust  and 
rubbish  derived  from  the  grain,  and  that  only  one  of  them  is 
actually  injuring  the  kernels;  and  a  thoro  examination  of  fair 


1912}          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  85 

samples  may  show  that  less  than  one  percent  of  the  kernels  are 
actually  injured.  Corn  in  the  ear  may  sometimes  be  sorted  to 
advantage,  if  infested,  with  a  view  to  removing  ears  showing 
injury  and  shelling  and  bagging  the  remainder.  A  general  infesta- 
tion may  often  be  checked  in  its  development  by  opening  the  ware- 
house in  winter  to  lower  the  temperature,  or  by  the  use  of  heat 
as  is  presently  to  be  described. 

If,  however,  it  appears  that  an  infestation  is  general  and  the 
injury  considerable,  and  that  simple  measures  will  not  be  sufficient, 
some  more  general  program  will  be  necessary.  If  fumigation  with 
either  carbon  bisulfid  or  hydrocyanic  acid  gas  is  practicable  under  the 
conditions,  this  is  by  all  means  the  most  effective  and  satisfactory 
process  in  such  cases;  but  this  requires  that  it  shall  be  possible  to 
make  the  granary  or  storeroom  virtually  gas-tight,  or  so  tight  that 
the  leakage  of  gas  will  be  so  slow  that  a  fatal  atmosphere  may  be 
maintained  for  a  period  of  several  hours. 

Hydrocyanic  acid  gas  is  the  more  poisonous  of  these  two  sub- 
stances, but  the  more  difficult  and  dangerous  of  application,  and 
as  it  has  comparatively  little  penetrating  power,  it  can  not  be  used 
against  insects  infesting  grain  in  bulk  or  against  those  which  are 
inclosed  within  the  kernel.  It  is  the  best  fumigant,  however,  for 
use  against  the  Mediterranean  flour-moth,  and  for  any  other  soft- 
bodied  insects  which  do  not  penetrate  deeply  into  the  grain.  Car- 
bon bisulfid  must  be  chosen  if  hydrocyanic  acid  gas  is  not  available. 
Even  where  the  storage  rooms  can  not  be  made  fit  for  the  fumiga- 
tion process,  it  may  be  possible  to  accomplish  the  purpose  by  con- 
structing a  special  room  or  even  erecting  a  small  separate  building 
thru  which  infested  material  may  be  passed  in  comparatively  small 
lots. 

Next  to  fumigation,  extremes  of  temperature,  especially  sudden 
changes  from  one  extreme  to  another,  are  on  the  whole,  the  most 
effective. 

FUMIGATION   WITH   HYDROCYANIC  ACID   GAS 

Preliminary  to  the  fumigation  of  a  mill,  warehouse,  or  granary, 
the  room  or  rooms  to  be  fumigated  should  be  thoroly  cleaned  and 
the  sweepings  burned.  This  operation  is  particularly  important, 
as  the  gas  to  be  used  has  little  penetrating  power,  and  living  in- 
sects nesting  away  in  a  pile  of  rubbish,  or  hidden  in  a'  crevice 
packed  with  dirt,  may  escape  uninjured.  Next,  everything  must 
be  done  to  make  the  place  tight,  windows  and  doors  receiving 
special  attention.  Cracks  around  window- frames  should  be  tightly 
stuffed  with  cotton  batting,  macerated  paper,  or  white  waste,  or 
else  thick  soft  paper  should  be  fastened  over  the  cracks  with  car- 
penters' glue  or  a  good  quality  of  flour  paste.  Broken  or  missing 
window-panes  should,  of  course,  be  replaced.  Keyholes  in  doors, 
and  spaces  between  the  door-frame  and  the  door  itself  should  be 


86  BULLETIN    No.    156  [July, 

similarly  closed.  All  outlets  to  the  room — ventilators,  registers, 
pipe  openings,  and  the  like,  as  well  as  cracks  in  the  floors,  ceilings, 
and  walls — should  be  stuffed  with  waste  and  covered  with  paper. 
As  carpenters'  glue  is  difficult  to  remove,  a  good  flour  paste  may 
be  substituted  for  it  where  this  is  a  matter  of  importance. 

Hydrocyanic  acid  gas  is  produced  by  the  reaction  of  cyanide  of 
potassium,  sulphuric  acid,  and  water,  the  gas  coming  off  with  a 
more  or  less  violent  bubbling  of  the  mingled  fluids.  The  gas 
evolved  is  one  of  the  most  prompt  and  powerful  poisons  in  com- 
mon use,  and  the  residue  left  after  the  reaction  is  sufficiently  poison- 
ous to  make  it  necessary  that  it  should  be  carefully  disposed  of 
by  burying.  The  cyanide  used  should  be  in  lumps,  and  98  percent 
pure.  To  insure  this  strength  a  reliable  brand  should  be  bought 
in  its  original  sealed  package.  That  manufactured  by  Merck  & 
Company,  of  New  York,  is  of  standard  quality  and  can  be  de- 
pended on.  Commercial  sulphuric  acid  is  of  sufficient  purity,  but 
it  should  have  a  specific  gravity  of  about  1.83  (66°  Beaume). 
Cyanide  should  be  protected  from  moisture  and  kept  in  sealed  ves- 
sels, as  it  is  otherwise  liable  to  decompose.  Gloves  should  be  worn 
while  handling  either  of  these  chemicals. 

To  determine  the  amount  of  the  ingredients  needed  for  fumiga- 
tion, one  must  first  find  the  cubic  contents  of  the  containing  room, 
making  no  allowances  for  furniture  or  other  objects  in  it.  An 
ounce,  by  weight,  of  cyanide,  and  a  fluid  ounce  of  commercial  acid 
are  needed  for  every  hundred  cubic  feet  of  space  in  the  room. 

Three-gallon  earthenware  jars  make  suitable  generators,  and 
these  should  be  provided  at  the  rate  of  one  for  every  five  thousand 
cubic  feet  of  space  to  be  fumigated.  As,  for  the  best  effect,  the 
gas  must  be  held  at  least  eighteen  hours,  the  importance  of  tight 
construction  is  manifest.  If,  however,  this  is  impracticable,  the 
strength  of  the  gas — the  amount,  that  is,  of  the  ingredients  per 
hundred  cubic  feet — must  be  increased  according  to  the  judgment 
of  the  operator.  In  some  cases  even  twice  the  above  quantities 
may  be  found  necessary  to  a  successful  operation. 

The  containers  should  then  be  distributed  thruout  the  room  or 
rooms  and  the  proper  amount  of  water  should  be  poured  into  each. 
The  sulphuric  acid  should  next  be  measured  out  and  gently  poured 
into  the  water.  The  cyanide  of  potash  should  be  prepared  for  use 
by  breaking  it  into  lumps  somewhat  smaller  than  an  egg.  This 
should  be  done  in  the  open  air.  It  should  then  be  carefully  weighed 
out  and  placed  in  thin  paper  bags  in  quantity  sufficient  for  each  of 
the  containers.  One  of  these  should  be  placed  by  the  side  of  each 
jar,  and  then  the  sacks  should  be  dropped  carefully  in  quick  suc- 
cession into  their  corresponding  jars  in  such  an  order  that  the 
operator  shall  not  be  exposed  to  the  evolving  vapors.  When  all 
is  done  the  exit  should  be  closed  and  locked,  and  a  conspicuous 
label  should  be  placed  outside  as  a  warning. 


i<)i2\          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  87 

Fumigation  should  be  done  on  a  quiet  day,  as  a  high  wind 
tends  to  blow  the  vapor  thru  such  openings  as  may  remain  in  the 
walls.  A  temperature  of  not  less  than  70°  is  to  be  preferred. 
Commonly  two  successive  treatments  three  or  four  weeks  apart 
are  necessary  to  complete  success. 

The  operator  must  bear  in  mind,  in  his  plans  and  procedure, 
that  everything  must  be  done  in  such  a  way  that  he  shall  not 
breathe  the  escaping  gas.  Milk,  meats,  and  other  moist  or  liquid 
food  materials,  should  be  removed  before  fumigating,  as  they  are 
liable  to  become  poisoned  by  absorption  of  the  gas.  Arrangements 
should  be  made  to  open  the  building  from  without  for  ventilation 
when  the  fumigation  is  completed,  and  it  should  not  be  entered 
until  it  is  practically  free  from  the  gas. 

FUMIGATION  WITH  CARBON  BISULFID 

This  volatile  and  exceedingly  ill-smelling  chemical  has  been 
more  or  less  used  against  stored  grain  insects  for  many  years,  but 
recent  experiments,  including  some  of  those  upon  which  this  dis- 
cussion is  based,  have  shown  that  the  strengths  at  which  it  must 
be  used  and  the  best  methods  of  its  application,  were  but  little  un- 
derstood, and  that  it  has  often  been  recommended  for  too  many 
purposes  and  for  use  under  really  impossible  conditions.  This 
has  resulted  in  many  failures  which  have  discredited  it  more  or 
less  as  an  insecticide  for  granary  and  warehouse  use. 

The  commercial  bisulfid  is  a  heavy,  oily  fluid  with  a  specific 
gravity  of  1.29,  boiling  at  115°  F.,  and  igniting  at  about  300°  F. 
It  is  cold  to  the  touch,  and  because  of  its  rapid  evaporation  it  pro- 
duces a  freezing  sensation  when  applied  to  the  skin.  When 
handled  in  quantity  one's  feet  are  likely  to  become  cold,  especially 
if  any  of  the  fluid  is  spilled  upon  the  shoes.  The  vapor  is  a  little 
over  two  and  a  half  times  heavier  than  air,  a  point  to  be  remem- 
bered in  application,  since  it  goes  first  to  the  bottom  of  the  in- 
closure.  When  mixed  with  air  it  becomes  inflammable  and  ex- 
plosive, especially  when  the  mixture  is  in  the  ratio  of  about  one 
part  of  the  vapor  to  fourteen  parts  of  air,  equivalent  to  fifteen 
pounds  of  the  fluid  to  a  thousand  cubic  feet  of  space.  Such  a  mix- 
ture of  air  and  bisulfid  vapor  may  be  exploded  by  so  small  a  cause 
as  the  spark  made  by  hitting  a  nail  or  by  turning  an  electric  light 
on  or  off,  instances  of  both  of  which  have  come  within  our  own 
experience.  The  chemical  leaves,  on  evaporation,  a  residue  of  im- 
purities which  stain  cloth  and  other  substances,  so  that  direct  con- 
tact with  it  should  be  avoided.  Its  rate  of  evaporation  is  in  pro- 
portion to  the  temperature  and  the  area  of  its  surface  of  exposure, 
being  very  rapid  when  exposed  in  shallow  vessels  and  at  a  high 
temperature.  Its  efficiency  is  also  the  greater  the  more  rapid  the 
evaporation  and  the  higher  the  temperature.  One  volume  of  the 


88  BULLETIN    No.    156  [July, 

liquid  will  produce  about  three  hundred  and  seventy-five  volumes 
of  the  vapor. 

There  is  one  effect  of  this  gas  upon  the  person  handling  it 
which  should  be  especially  borne  in  mind.  When  evaporated  by 
spraying  or  sprinkling,  or  by  exposing  in  many  wide  and  shallow 
dishes,  it  accumulates  very  rapidly  in  the  air,  and  unless  one  is 
careful  it  will  soon  affect  him  dangerously.  Operators  in  large 
storage  rooms  applying  the  fumigant  by  means  of  a  spray  have 
become  unconsciously  intoxicated  by  it,  and  are  liable  to  be  over- 
come, with  dangerous  or  even  fatal  consequences.  The  sense  of 
smell  becomes  benumbed,  hearing  and  sight  are  dulled,  the  action 
of  the  heart  becomes  quick  and  violent,  and  the  mouth  dry  and 
parched.  If  these  symptoms  appear,  the  operator  should  at  once 
abandon  his  task.  A  serious  intoxication  may  last  for  several  hours, 
accompanied  by  headache  and  followed  by  a  taste  of  the  bisulfid 
in  the  mouth  for  a  day  or  two. 

Altho  carbon  bisulfid  was  formerly  supposed  to  be  available 
only  for  grain  in  bulk,  and  not  permissible  for  flour,  it  is  now 
known  that  it  may  be  used  in  mills  without  fear  of  injuring  the 
flour  in  any  way.  The  method  of  its  use  will  vary  somewhat  ac- 
cording to  the  conditions  present,  but  the  fluid  should  be  evaporated 
as  rapidly  as  possible,  and  the  vapor  should  be  given  off  from  as 
high  a  place  as  possible  within  the  inclosure.  A  moderately  high 
temperature  is  to  be  preferred,  but  is  not  indispensable.  The  best 
method  of  distributing  the  fluid  is  by  means  of  an  atomizer  or  a 
spray  pump.  If  the  latter  is  used,  the  liquid  may  be  sprayed 
directly  upon  the  ceiling;  or  it  may  be  simply  sprinkled  over  the 
exposed  surface  from  a  watering-pot. 

When  these  methods  are  impracticable,  it  will  accomplish  the 
pu'rpose  if  it  is  placed  high  up  towards  the  ceiling  in  large,  very 
shallow,  dishes  or  pans,  the  sides  not  more  than  a  quarter  of  an 
inch  in  height.  Bags  of  cotton-seed  or  grain  may  be  treated 
separately  by  means  of  an  iron  tube,  provided  with  a  conical  tip, 
and  pierced  along  its  sides  with  holes  to  permit  the  escape  of  the 
liquid  and  vapor.  In  most  cases,  however,  this  individual  treat- 
ment will  be  found  unnecessary. 

Our  recent  experiments,  carried  on  with,  great  care  and  dupli- 
cated many  times,  have  convinced  us  that  an  effective  fumigation 
requires  ten  pounds  of  carbon  bisulfid  to  every  thousand  cubic  feet 
of  space  to  be  treated.  At  this  strength  we  have  found  the 
fumigant  effective  against  all  granary  pests  and  at  all  temperatures. 
An  effective  treatment  presupposes  a  construction  of  the  granary 
or  bin  such  as  to  hold  the  vapor  for  several  hours  without  serious 
loss  by  leakage.  It  is  at  this  point  that  most  persons  fail  in  prac- 
tical work,  since  few  storehouses  or  granaries  are  sufficiently  tight 
to  hold  the  vapor  long  enough,  without  special  and  careful  prep- 
aration. 


1912]          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  89 

To  protect  one's  grain  or  other  property  against  insect  pests 
he  must  either  build  his  granary  or  storerooms  in  such  a  way  as 
to  permit  effective  fumigation,  or  he  must  provide  a  properly  built 
room  to  be  used  especially  for  fumigation  of  infested  materials. 
This  room  may,  of  course,  be  of  any  convenient  shape,  but  it  should 
not  have  more  windows  or  doors  than  necessary,  and  it  should 
not  contain  more  than  fifteen  thousand  cubic  feet  of  space.  The 
walls,  ceiling,  and  floor  should  be  similarly  constructed — built,  that 
is,  of  two  layers  of  seasoned,  grooved  flooring  of  good  quality,  the 
outer  layer  running  at  right  angles  to  the  inner,  and  with  glazed 
building  paper  between  the  two.  Care  must  be  taken  with  this 
layer  of  paper,  as  it  is  an  important  part  of  the  structure.  Wherever 
the  edges  are  joined  they  should  be  broadly  overlapped  and  secured 
by  gluing.  The  door  should  be  similarly  constructed.  The  in- 
terior of  the  building  should  have  all  cracks,  crevices,  and  holes 
closed  by  putty,  after  which  it  should  receive  a  heavy  coat  of  paint 
and  should  then  be  lined  thruout  with  linen  cloth  stretched  tight, 
lapped  at  the  edges,  and  held  in  place  by  lathing.  This  cloth  should 
be  so  placed  that  the  laps  do  not  come  at  the  corners  of  the  room, 
and  it  should  be  finally  coated  with  moderately  thick  carpenters' 
glue,  which  substance  has  the  great  advantage  that  it  is  insoluble 
in  carbon  bisulfid.  It  must,  however,  be  renewed  if  it  cracks  and 
scales  off,  as  is  sometimes  the  case,  especially  when  the  lumber  is 
not  well  seasoned.  The  door  should  be  treated  like  the  walls.  It 
should  fit  as  tightly  as  possible,  and  clamps  similar  to  those  on 
refrigerator  doors  should  be  used  to  batten  it. 

THE  USE  OF   COLD   AND   HEAT 

It  is  a  well-known  fact  that  insects  are  peculiarly  sensitive  to 
sudden  and  extreme  changes  in  temperature,  and  under  storage 
conditions  this  susceptibility  can  often  be  made  use  of  to  excellent 
advantage.  A  zero  temperature  following  upon  one  of  50°  or 
60°  F.,  and  quickly  followed  again  by  a  temperature  of  100°  or 
more,  will  commonly  kill  every  insect  in  an  infested  mill  or  storage 
room.  Where  steam  heat  can  be  applied,  especially  in  northern 
Illinois,  granary  pests  can  thus  be  readily  exterminated.  Indeed, 
a  temperature  of  125°  to  130°  F.  maintained  for  several  hours 
by  artificial  means  will  itself  destroy  most  insects;  but  for  this 
it  is  necessary  to  provide  steam  radiators  near  the  floor,  to  use 
direct  steam  under  pressure,  and  to  close  down  the  mill  or  other 
building  for  about  twenty-four  hours. 

CONTACT  INSECTICIDES 

In  cleaning  up  infested  places,  cracks  in  the  floor,  walls,  and 
ceiling  must  often  be  treated  in  a  way  to  destroy  the  insects  con- 


90  BULLETIN   No.   156  [July, 

cealed  within  them.  Gasoline  and  benzine  are  both  excellent  for  this 
purpose,  provided  fire  and  lights  be  kept  away  from  them  until 
they  have  evaporated,  as  of  course  they  presently  do.  They  may 
be  applied  in  any  convenient  way — by  .brushing,  sprinkling,  or 
spraying,  according  to  the  conditions  present.  They  act  at  once 
upon  contact,  and  if  doors  and  windows  are  opened  immediately 
after  the  application  the  vapors  will  soon  disappear. 

A  KEY  FOR  THE  IDENTIFICATION  OF  GRANARY  INSECTS 

This  table  is  introduced  to  enable  practical  grain  men  and 
millers  to  identify  insects  found  injuring  stored  grains  and  their 
products.  It  is  simply  a  working  table  for  the  most  important  of 
these  insects,  and  does  not  include,  of  course,  all  insects  to  be 
found  in  stored  grain  or  in  mills,  some  of  which  may  be  merely 
feeding  on  debris.  The  table  is  as  free  from  technicalities  as  it  is 
possible  to  make  it.  It  should  be  remembered  that  all  of  these 
insects  have  four  distinct  stages  of  development,  proceeding  in 
succession  from  the  egg  to  larva,  pupa,  and  adult;  also  that  all 
adult  insects  have  six  legs,  neither  more  nor  less,  and  that  all  here 
considered  have  two  pairs  of  wings. 

A.  Moths  or  millers:    the  larva  a  caterpillar  with  distinct  head, 

three  pairs  of  thoracic  legs  and  five  pairs  of  abdominal  legs, 

one  of  these  pairs  on  the  last  segment.     The  larva  usually 

spins   a   cocoon;    the   pupa   is   brownish,   its   appendages   not 

free.     The  adult  insects  have  two  pairs  of  wings,  the  front 

pair  longer  and  usually  more  colored  than  the  lower  or  hind 

pair,  which  are  usually  grayish.    Their  bodies  are  soft,  pliable, 

and  covered  with  microscopic  scales,  like  dust,  and  fine  hairs. 

Insects  of  medium  size,  usually  about  half  an  inch  long. 

a.  A  small  whitish  caterpillar,  living  in  grains  of  corn  or  wheat, 

eating  out  the   embryo  and   other   soft  portions,   pupating 

within  the  grain,  and  emerging  thru  a  round  hole  at  or  near 

the  tip  of  the  kernel;   this  hole  is  covered  with  silk.     Badly 

infested  ears  of  corn  look  as  if  riddled  with  shot.     Adult 

moths  grayish   clay-yellow,   small 

The  Angoumois  Grain  Moth. 

aa.  Caterpillars  which  spin  much  silk,  usually  forming  a  silken 
tube  to  which  they  retire;  this  tube  covered  with  particles 
of  whatever  substance  they  happen  to  be  feeding  upon. 
Living  in  flour,  meal,  or  chaff,  sometimes  among  grain,  or 
in  food  substances  such  as  prepared  cereals.  The  full- 
grown  caterpillars  make  a  cocoon. 

b.  A  free-living  caterpillar  usually  not  concealed  within  a 
silken  tube,  olive-green  to  pinkish  in  color,  infesting 
grain  or  meal,  webbing  particles  together,  covering  bags 


I9i2\          INSECTS  INJURIOUS  TO  STORED  GRAINS  AND  THEIR  PRODUCTS  91 

of  grain  with  a  web  of  silk,  and  generally  scattering  silk 
in  all  directions.  The  moth  has  the  outer  two-thirds  of 
the  fore  wing  reddish  brown  with  the  luster  of  copper, 
while  the  inner  or  basal  third  is  soiled  grayish;  its  hind 
wings  are  grayish.  The  cocoon  is  elliptical,  slender, 

fragile,  and  of  clear  silk The  Indian  Meal  Moth- 

bb.  Caterpillars  living  in  densely  woven  silken  cases  which 
are  covered  with  particles  of  the  food  substance.  Com- 
mon in  flour  or  chaff  in  corners. 

c.  A  yellowish  white  to  pinkish  caterpillar  living  in  flour, 
webbing  it  together  and  forming  a  cocoon  covered  with 
particles  of  flour.  The  moth  is  dark  grayish,  the  fore 
wings  silvery  gray  mottled  with  blackish  streaks,  one  of 
which,  obscurely  resembling  a  letter  V  or  W,  crosses  the 
wing  between  its  base  and  middle;  the  hind  wings  are 
silvery  whitish The  Mediterranean  Flour-moth. 

cc.  A  soiled  grayish  caterpillar,  darker  at  each  end,  living 
in  chaff  or  other  vegetable  debris  in  dark  damp  places, 
securely  webbing  the  food  substance  together  so  that  it 
becomes  matted;  larval  case  and  cocoon  completely  hid- 
den, covered  \Vith  the  food  substance.  Adults  very  beau- 
tiful, base  and  outer  portions  of  the  front  wings  brown- 
ish red,  the  middle  portion  whitish,  margined  on  each 
side  by  a  thin  wavy  whitish  line  which  crosses  the  wing 
and  separates  the  three  color  divisions.  The  hind  wings 
are  whitish,  with  a  whitish  wavy  line  running  thru  them 

and  a  row  of  black  spots  around  the  hind  margin 

The  Meal  Snout-moth. 

A  A.  Beetles  or  weevils;  the  larva  or  grub  with  a  distinct  head, 
usually  three  pairs  of  thoracic  legs  but  no  abdominal  legs,  bit- 
ing jaws.  Does  not  spin  a  cocoon.  The  pupa  is  whitish,  the 
appendages  free.  The  adults  are  hard  and  horny,  with  two 
pairs  of  wings,  the  upper  pair  horny,  closed  together  in  a 
straight  line  over  the  back,  and  concealing  the  larger,  folded, 
thin  under  pair.  Their  mouths  are  constructed  for  chewing; 
placed  in  weevils  at  the  tip  of  a  snoutlike  prolongation  of  the 
head.  Insects  differing  much  in  size;  usually  about  as  large 
as  a  grain  of  wheat,  but  varying  up  to  a  half-inch  or  more  in 
length. 

d.  Small  insects  living  in  kernels  of  grain,  or  among  grain  and 
other  stored  products. 

'e.  A  very  small,  fat,  humped-up  grub,  occurring  in  kernels  of 
wheat  or  corn,  like  the  grub  in  chestnuts  but  smaller, 
yellowish  white,  legless,  very  hump-backed  and  wrinkled, 
unable  to  crawl,  its  head  inconspicuous  and  yellowish 


92  BULLETIN    No.    156  [July. 

brown.  The  pupa  is  found  within  the  kernel.  The  adult 
is  smaller  than  a  grain  of  wheat,  with  a  snoutlike  pro- 
longation of  the  head,  and  elbowed  feelers  attached  to 
the  snout.  Two  brownish  species,  which  feign  death 
when  disturbed.  In  ears  of  corn  their  work  is  very  sim- 
ilar to  that  of  the  Angoumois  grain  moth,  previously 
described. 

/.  The  adult  beetle  is  chestnut-brown,  without  spots  on  its 
upper  wings.  A  slightly  larger  weevil  than  the  next, 

more  common  in  the  North 

The  Granary  or  Black  Weevil. 

ff.  The  adult  beetle  is  somewhat  duller  brown  than  the  pre- 
ceding with  four  reddish  spots,  one  on  each  outer  cor- 
ner of  the  upper  wing.  A  southern  species 

The  Rice  or  Spotted  Weevil. 

ee.  Small,  more  or  less  slender,  somewhat  flattened  grubs, 
with  distinct  head  and  thoracic  legs,  crawling  about  in 
the  debris  of  various  grains  or  their  products,  or  in  veg- 
etable foodstuffs.  The  adults  are  flattened,  longer  than 
wide,  the  head  not  prolonged  into  a  snout.  They  occur 
with  the  grubs,  actively  feeding.  Two  distinct  species 
and  their  allies;  all  small. 

g.  The  grub  uniform  in  color,  whitish,  about  a  quarter  of 
an  inch  long,  slender,  its  head  narrower  than  the  first 
body  segment;  pupa  with  the  thorax  not  toothed  laterally, 
but  with  most  of  the  abdominal  segments  bearing  a 
toothlike  lobe,  acute  at  each  outer  corner  and  toothed 
along  its  sides.  The  adult  beetle  is  active,  smooth,  el- 
liptical, and  reddish  brown.  The  Confused  Flour-beetle. 

gg.  The  grub  whitish,  with  a  rectangular  yellowish  area 
on  each  segment  above,  only  the  margin  whitish  as  seen 
from  above;  the  head  broader  than  the  first  body  seg- 
ment. The  pupa  bears  along  each  side  of  the  thorax  and 
abdomen  a  series  of  stout  lobelike  teeth,  which  are  cy- 
lindrical-rectangular and  blunt.  The  adult  beetle  is 
smaller  than  in  the  preceding  species,  color  dark  choco- 
late-brown, the  sides  of  the  thorax  toothed  like  a  saw. . 
The  Saw-toothed  Grain-beetle. 

dd.  Large  insects,  living  concealed  in  the  bottoms  of  bins,  cor- 
ners, and  the  like,  feeding  upon  flour,  meal,  or  bran.  The 
adults  are  large  black  beetles;  the  larvae,  large,  cylindrical, 
wormlike  creatures,  resembling  wireworms. 

h.  The  adult  not  quite  black  in  color,  shining,  its  third  an- 
tennal  joint  not  quite  twice  as  long  as  the  second;  larva 
light  yellowish,  shining ....  The  Yellow  Meal-worm  beetle. 

hh.  The  adult  black  and  without  luster,  its  third  antennal 
joint  thrice  as  long  as  the  second;  larva  very  dark,  shining. 

. .  The  Dark  Meal-worm  beetle. 


-5 


•PPH 


UNIVERSITY  OF  ILLINOIS-URBANA 

Q.630.7IL6B  C001 

BULLETIN.  URBANA 
153-1651912-13 


30112019528428 


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